89012-55-5Relevant academic research and scientific papers
Direct synthesis of protected arylacetaldehydes by tetrakis(phosphane)- palladium-catalyzed arylation of ethyleneglycol vinyl ether
Kondolff, Isabelle,Doucet, Henri,Santelli, Maurice
, p. 765 - 774 (2007/10/03)
A range of aryl bromides undergo Heck reaction with ethylene glycol vinyl ether, in the presence of [PdCl(C3H5)]2/ cis,cis,cis-1,2,3,4-tetrakis[(diphenylphosphanyl)methyl]cyclopentane as catalyst, to give regioselectively protected arylacetaldehydes in good yields. The β-arylation products were obtained in with 93-100 % selectivity with electron-poor aryl bromides or heteroaryl bromides. Furthermore, this catalyst can be used at low loading, even for reactions with sterically hindered aryl bromides. The aryl vinyl ether intermediates undergo subsequent ketalisation to give the corresponding 2-benzyl-1,3-dioxolane derivatives. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
Direct synthesis of protected arylacetaldehydes by palladium- tetraphosphine-catalyzed arylation of ethyleneglycol vinylether
Kondolff, Isabelle,Doucet, Henri,Santelli, Maurice
, p. 1561 - 1564 (2007/10/03)
Through the use of [PdCl(C3H5)]2/cis,cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl) cyclopentane as a catalyst, a range of aryl bromides undergo Heck reaction with ethyleneglycol vinylether to give regioselectively protected arylacetaldehydes in good yields. The β-arylation products were obtained in the range 93-98% selectivity with electron-poor aryl bromides. Furthermore, this catalyst can be used at low loading, even for reactions of sterically hindered aryl bromides. The arylvinyl ethers intermediates undergo subsequent ketalization to give the corresponding 2-benzyl-1,3-dioxolane derivatives.
Palladium(II)-Catalyzed Acetalization of Terminal Olefins Bearing Electron-Withdrawing Substituents with Optically Active Diols
Hosokawa, Takahiro,Ohta, Toshiyuki,Kanayama, Satoshi,Murahashi, Shun-Ichi
, p. 1758 - 1764 (2007/10/02)
Terminal olefins bearing electron-withdrawing substituents such as CH2=CHCOR (R=Ph, Me, t-Bu), CH2=CHCOOMe, and CH2=CHCN are regioselectively acetalized at the terminal carbon (C1) by diols in the presence of PdCl2 (0.1 equiv) and CuCl (1 equiv) in DME at 50 deg C under an atmosphere of O2 (1 atm).The use of optically active (R,R)-2,4-pentanediol (4) gives homochiral cyclic acetals of aldehyde precursors in good yields.The acetalization of CH2=CHCOR is accompanied by the formation of Michael-type adducts such as 3a (R=Ph).However, of importance is that their formation can be prevented by the use of Na2HPO4 as an additive.Although in an early stage of the reaction of CD2=CHPh with 4, a statistical d scrambling of the starting olefin occurs, no such scrambling is observed with CD2=CHCOPh.Additionally, the acetalization of CD2=CHCOPh with 4 results in 1,2 deuterium migration, together with 25percent d loss.These results are accounted for by the reaction pathways involving oxypalladation, Pd-H elimination, and subsequent ring closure giving enol ether.A catalytic cycle involving the oxygenation of Pd-H species with molecular oxygen is proposed.
Palladium(II)-catalysed Acetalization of Terminal Olefins Bearing Electron-withdrawing Substituents with 1,3- and 1,2-Diols
Hosokawa, Takahiro,Ohta, Toshiyuki,Murahashi, Shun-Ichi
, p. 848 - 849 (2007/10/02)
Treatment of terminal olefins bearing electron-withdrawing groups with (R,R)-pentane-2,4-diol (2) in the presence of PdCl2-CuCl-O2 in 1,2-dimethoxyethane gives cyclic acetals such as (3) and (12b) via attack at the terminal carbon atom; the corresponding acetals are similarly formed from propane-1,3-diol (5) and ethylene glycol (8).
